Why it shows less space for memory devices

We all have noticed that we can not use the full space in our memory devices. It always shows less space that we are supposed to get. My article gives an explanation on this storage deduction from our memory devices.

Since long I have seen on my PC, storage devices always shows less space than its original space. The common answer I got was like this "OS takes that space for some processes and that's why the available space is less". But as time goes by I am sure all of us know the reason. But still just to have the real reason to be available in our knowledge base(DotNetSpider)I thought of explaining it.

Recently I bought a 500GB Western Digital external hard drive but when I plug it in my laptop it shows 465GB available memory space. Where is the rest 35GB?

Our operating system is a program and according to that the memory space is calculated in this way

1024 bytes = 1 KB1024 KB = 1 MB1024 MB = 1 GB.

But the manufacturer companies calculate the memory space in the following way

1000 bytes = 1 KB1000 KB = 1 MB1000 MB = 1 GB

So when a hard drive company manufactures a hard drive of 500 GB then the space in bytes will be 500*1000*1000*1000 = 500000000000bytes. Now when this hard drive is connected with computer then the space is calculated by the OS. The space conversion will be